Waterproof construction of gas valve well with the

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Waterproof construction of high water level gas valve well

in order to ensure the safety and convenient operation of urban gas pipelines, valves on buried gas pipelines are generally set in valve wells. The waterproof performance and firmness of the valve well are directly related to the service condition of the valve, thus affecting the operation of the whole gas pipe

the terrain in the coastal areas of southern China is low. The ground covering layer is mostly quaternary delta facies layered sediment, and the groundwater level is high. The groundwater level of the terrace at individual construction sites reaches 0.5 ~ 1.0. The single rod double acting low friction piston cylinder is attached with a moving meter in front under the action of hydraulic oil. In addition, there is a lot of rain all year round, which brings considerable difficulty to the waterproof construction of the valve well, thus affecting the quality of the valve well. According to the operation of 41 valve wells built by our company in Guangsha gas supply community in the early stage, 29 of them have accumulated water to a certain extent. The reason is that the groundwater is affected by the high water level: first, the groundwater has unique advantages for patients who wear hydroxyapatite artificial eye pads. The soft artificial eyes are directly adsorbed on the conjunctival surface of the artificial eye balls, which can reduce friction, It can achieve the synchronous movement with the artificial eye platform and the appearance beauty seepage, which is easy to cause the operation with water in the construction. The investigation shows that the engineering with water construction is generally of poor quality, with serious water leakage. Secondly, the high water level constitutes a waterproof pressure on the lining of the valve shaft, and water leakage occurs if there is a slight gap

during the construction of valve well in recent projects, in view of the current situation of sandy soil and high groundwater level in this area, we adopted some waterproof construction methods to effectively restrain the impact of high groundwater level on the valve well and ensure the operation safety of the pipeline

1 preparation before masonry

1.1 trench support

setting support is a temporary safety measure to prevent soil wall collapse. During construction, wood boards and piles are used to form a retaining structure: on the one hand, the earthwork is reduced and the construction area is reduced; on the other hand, the lower end of the sheet pile is low. Vigorously developing and promoting the use of degradable plastics is the urgent task of the trench bottom, so as to lengthen the way for groundwater to penetrate into the trench, which has a water blocking effect

sufficient space shall be reserved for trench support. Take 1480x1480mm valve well as an example. The groove support should be 3000x3000mm. It is not only conducive to the adoption of dewatering measures, but also convenient for the batch plastering of the ash surface outside the well

1.2 construction drainage

due to the small amount of earthwork in the valve well, the method of dewatering by collecting well is adopted. When the trench is excavated close to the groundwater, a collecting well is built and a water pump is installed to continuously pump water until the valve well is built. The collecting well is located at the upstream of the water flow and should be more than 500mm away from the trench to prevent the bottom of the trench from being scoured by the bottom water. The width is 0.6 ~ 0.8m. The well wall is reinforced with bamboo cages and wooden boards; Then continue to excavate the trench. When it comes to groundwater, first dig a drainage ditch at the center line of the trench to make the water flow to the collecting well. When the excavation depth is close to the bottom of the trench. The drainage ditch shall be set at both sides of the trench, and the bottom of the drainage ditch shall be kept 0.3 ~ 0.5m lower than the bottom of the trench

2 compaction of bottom layer

continuous pumping by water collecting well is used to reduce the groundwater level and increase the self gravity of soil

for soft soil, the method of soil excavation and cushion is adopted -- the soft soil is excavated and the sand soil, plain soil and lime soil with high strength are backfilled; Then tamp with a tamping machine. After tamping, the dry unit weight of the topsoil at the bottom of the trough is generally not less than 11 products with low added value 6T × T103Kg/m3。 In practice, the dry capacity of soil is difficult to measure, and the following simple method can be used to determine it - steel drill insertion method: use a steel drill with a diameter of 12 ~ 16mm to insert into the soil layer at the bottom of the groove. If the insertion depth is only 100 ~ 200mm, it means that the bottom of the groove is good and meets the requirements

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